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Jan. 31, 1956 L. HERELE ET AL PRODUCTION OF STAPLE FIBRES FROMPOLYAMIDES Filed March 5, 1952 6 Sheets-Sheet 1 INVENTORS LU IG HERELEKU JEHLE KA KU PA M5 ER PAUL. SCHLACK THEIR ATTORNEYS Jan. 31, 1956 L.HERELE ETAL 2,733,122

PRODUCTION OF STAPLE FIBRES FROM POLYAMIDES Filed March 5, 1952 6Sheets-Sheet 2 1 a It 2 A, I 27 Fig. 3 Fig. 3 Fig. 4

INVENTOR5 LUDWIG HERELE KURT JEHLE KARL KUNZ PAUL. MOLLER PAUL SCHLACKTHEIR ATTORNEYS Jan. 31, 1956 HERELE 5 AL 2,733,122

PRODUCTION OF STAPLE FIBRES FROM POLYAMIDES Filfld March 5, 1952 6Sheets-Sheet 3 NVENTORS WIG HEREIJ KURT JEHLE gm KARL- KU PAUL Mbl.

PAUL SCHLACK THEIR ATTORNEYS Jan. 31, 1956 1.. HERELE EI'AL 2,733,122

PRODUCTION OF STAPLE FIBRES FROM POLYAMIDES Filed March 5, 1952 6Sheets-Sheet 4 INVENTORS LUDWIG- HERELE KURT JEHLE KARL K NZ PAUL M LLERPAUL SCHLkCK WMS HEIR ATTORNEYS Jan. 31, 1956 L. HERELE ETAL 2,733,122

PRODUCTION OF STAPLE FIBRES FROM PQLYAMIDES Filed March 5, 1952 6Sheets-Sheet 5 INVENTORS LUDWIG HERELE KURT JEHLE 4. KARL K PNZ PAULMOLLER PAUL SCHLACK THEIR ATTORNEYS Jan. 31, 1956 L. HERELE ETAL2,733,122

PRODUCTION OF STAPLE FIBRES FROM POLYAMIDES Filed March 5, 1952 sSheets-Sheet 6 THEIR ATTORNEYS United States Patent M PRODUCTION OFSTAPLE FIBRES FROM POLYAMIDES Ludwig Herele, Kurt Jehle, Karl Kunz, PaulMiiller, and Paul Schlack, Bobingen, Germany, assignors to BobingenAktiengesellschaft fur Textii-Faser, Bobingen, Germany, a corporation ofGermany Application March 5, 1952, Serial No. 274,958 In SwitzerlandOctober 5, 1949 Public Law 619, August 23, 1954 Patent expires October5, 1969 16 Claims. (Cl. 18-54) This invention relates to certainimprovements in the production of staple fibres of polyamides.

Staple fibres of linear polyamides can be worked up with good successboth in wool and in cotton spinning mills.

In order to ensure smooth spinning of these fibres in the variousspinning machines and in order to obtain yarns of a high quality, thestaple fibres to be worked besides good technological properties as totensile strength and elongation must have a definite and durablecurliness.

It is an object of the present invention to provide a method by whichfibres meeting these requirements can be produced in a reliable andeconomic manner.

Another object of the invention is to provide a system which permits theproduction of fibres in accordance with these requirements in acontinuous process.

The present invention is based on the observation that in order to meetthe requirements above referred to, a specific combination of featuresregarding the chemical composition of the fibre material and featuresregarding the physical treatment of such fibres must be adhered to.Therefore, according to the present invention staple fibres are producedfrom a low of at least 40,000 deniers of polyamides (obtained, forinstance, by the process described in detail in the prior Patent2,241,321 of one of the co-inventors of the present invention) composedsubstantially of condensation products of the epsilon-aminocaproic acidand still containing watersoluble monomers or lowly polymeric compounds,by the steps of stretching the tow continuously to a multiple of itslength, washing it out with hot Water, treating it with a softeningagent, if desired, while being under tension, drying to a degree ofmoisture of less than percent, preferably less than 4 percent whilemaintaining the tension, crimping by a mechanical process and atelevated temperature, preferably by stufiing, and finally cutting thefilaments to the desired staple length, whereupon the staple fibres canimmediately be opened by blowing at them a jet of air, and dischargedsaid steps directly succeeding each other in this order, in a continuousprocess.

For the purpose of the present specification the term condensationproducts of the epsilon-aminocaproic acid" is intended to include notonly filaments obtained by the condensation of aminocaproic acid butalso filaments obtained by other processes, more particularly by thepolymerisation of epsilon-caprolactam which is sometimes referred to asa polyamide-forming derivative of the aminocaproic acid, provided onlythat the resulting filaments have a chemical structure which isidentical to that obtained by the condensation of theepsilon-aminocaproic' acid. By way of alternative, the polyamides inquestion could be defined as polyamides of the type yielding thehydrochloride of the aminocaproic acid when subjected to hydrolysis withhydrochloric acid.

Our novel process starts from a tow containing watersoluble monomericand/ or water-soluble lowly polymeric 2,733,122 Patented Jan. 31, 1956constituents, generally in quantities of 4 to 15 percent by weight.Hence, it is not necessary to remove the monomeric and the lowlypolymeric constituents before spinning the polyamide, but it is alsopossible to apply the method to polyamide fibres whose contents ofwatersoluble constituents has been reduced to less than 4 percent byspecial measures during the continuous polyierisation process, forinstance, by vacuum evaporation or by extraction of the polyamide beforethe working-up by the well-known process of melting the material on agrid. Preferably tows are used which have been obtained by directspinning of continuously produced melts of polymers.

The process according to the invention will at first be described in ageneral way:

The filaments drawn Off from the rolls coming from the spinning machineare united to form a bundle of parallel filaments which are at firstcontinuously oriented in conventional manner by stretching betweenroller aggregates. In case of stretching without heating a draft ofabout 123.5 to 1:45 is to be applied. Advantageous ly the tow isadditionally stretched at an elevated temperature, e. g., between and Inthis case, owing to the facilitation of the molecular flow a higherdraft of about 1:4.5 or 125.5 can be applied and it is possible tostretch each fibre to a particularly fine titre, e. g., of 1.2 to 2 den.Moreover, this method offers further advantages which will behereinafter explained.

After the stretching the filament tow is passed under tension throughhot, preferably boiling water in order to wash out the water-solubleconstituents from the filaments. Textile treating agents, such aswetting and dispersing agents, may be added to the hot water in order toremove from the filaments the finishing agents originating from thespinning process. In some instances, solvents may be used instead ofwater. The washing time may be, for instance, 60 to 300 seconds,depending'on the thickness of the filament bundles.

Following the washing process the filament bundles may be treated withother agents in one or more further vats, e. g., with oiling orsoftening agents, tanning agents, or dyestuffs. These treatments alsoare carried out while the filament tow is under tension, preferablymaintaining the circumferential speed of the first treating roller whichin turn is usually somewhat reduced in relation to the circumferentialspeed of the stretching frame, in order to equalize the preliminarytension originating from the stretching process. In this connection itshould be noted that by way of alternative the oil or softener requiredfor the further treatment of the fibre may be applied entirely or partlyafter the cutting. The softening agents may consist of stea'rylpolyglycol, polyglycolether from the alcohols obtained by reduction ofmixtures of fatty acids from palm kernels, if desired in connection withsalts improving the antistatic effect, such as, magnesium chloride,sodium nitrate, triethanol amine-lactate. The deposits of softeningagents on the fibre are in general between 0.4 and 1 percent by weight.

The filament tow is then further dried under tension to an amount ofmoisture of less than 10% and either sub jected to a second stretchingtreatment, at an elevated temperature, or immediately crimpedmechanically at an elevated temperature, e. g., by gear wheels, orpreferably by stufiing. The material which still shows internal tensionsis preferably crimped at a temperature above 80' ing between 80 C. and130 C. It is also possible to apply high frequency heating. Finally, thecontinuous filaments are cut to staple length. The staple fibres may beopened individually by blowing with a brisk air current and delivered toa store tank. The tension to be maintained from the stretching up to thefeeding of the filaments to the curling device may vary within certainlimits, depending on the desired type of fibre. The tension required forproducing a fibre of the wool type is less than that required for afibre of the cotton type. erally speaking, it can be said that thetension of a stretched filament bundle of 40,000 denier amounts to about140 kilograms after the stretching and before the washing. After thewashing and before the drying the tension of the humid cable is about100 kilograms, and after the drying it rises again to 150 kilograms.

Our novel process is particularly advantageous since it permits theproduction, in a continuous process starting from the stretching, of apermanently curly fibre tuft. Thus, the conventional devices foropening, e. g., pickers or shakers and the like, can be dispensed with.Our novel method permits the production of a fibre having a relativelylow breaking dilatation or elongation at rupture without a detrimentaleffect to the fibre. Moreover, the curly fibre obtained according to thepresent invention is more suitable for an after-treatment with tanningagents than a comparable fibre which after the crimping containsmonomeric lactam in quantities, for instance, of 5 percent or more.

All percentages or proportions in the specification and claims are byweight, temperatures in Celsius.

Our novel process is equally suitable for the production of long-stapledfibre with any form of crimps adapted for working up after the worstedspinning process and for short-fibred and possibly less intensivelycrimped material to be worked up after the methods used in the cottonand schappe spinning mills. With curly staple fibres of the cotton typeproduced from polymeric epsiloncaprolactam by conventional processes, ithas been ob served that only a relatively light crimping in connectionwith a tanning treatment, e. g., with tannin or with synthetic oxysulfontanning agents permitted the passage through the carding machine whileit was now found that fibres produced by our novel process being treatedwith tanning agents but being crimped relatively intensively show a morefavorable behaviour than less intensively crimped fibres as to theirstability in the carding operation. In order to produce a particularlyfine fibre material, e. g., of a single titre of 1.2 to 2.0 denier,adapted for working up according to the silk and cotton spinning system,the tow according to the invention is preferably stretched in a hotcondition, e. g., between 140 C. and 135 C., and with a high stretchingratio, e. g., of 1 :4 to 1:55. In this case it may be advisable toattenuate the very high preliminary tension by a somewhat higherreduetion of the circumferential speed or delivery of the treatingrollers compared to the delivery of the stretching device.

It will be understood that the operations following the crimping of thethus treated filaments, i. e. the cutting and opening, can also be.carried out, in a sequence of operans p ately om the pre ed n a m nt s tthe place and time of the treatment, if desired, provided that thecrimped filaments are stored and transported in such a way that thecrimping is not impaired thereby. However, it is important that theprocess up to this stage, i. e. including the crimping operation, iscarried out in a continuous series of operations directly succeedingeach other, not only for economic reasons, but also because it isimportant to adapt the, residual moisture of the tow, which can. easilybe controlled in the drying operation, to the actual requirements of thecrimping operation. The crimping will be increased with increasingmoisture in case of unchanged pressure and moreover the lustre of theflocks is reduced so that the material obtains a char- Genacter moresimilar to wool. Moreover, the method offers the advantage that thematerial heated on the drying cylinder to about C. is fed directly intothe crimping equipment, whereby less heating of the crimping equipmentis required.

In order to obtain an approximately uniform crimping efiect withincreased moisture, it is necessary, in case of unchanged pressure, toslightly reduce the temperature. The upper temperature limit which isdefined by the beginning of agglutination, is reduced with increasingmoisture in the cable.

We have found that the quality of the crimping can also be improved byallowing the fibre material leaving the stufiing apparatus in a hotcondition to stay in a discharge channel directly following the stuffingchannel, while maintaining the compressed shape, for a short time, about1 to 2 minutes, with gradual cooling, before exposing it to the draft ofthe cutting device.

Our novel process is preferably carried out by a system comprising a perse known stretching frame having two roller aggregates driven atdifferent speeds, which may be followed by a second stretching frameoperating at elevated temperature, and/or means for a wet treatment ofthe fibres under tension, at least one vat for liquid treatment withcylindrical rotary feed members arranged therein transversely to thetravelling direction of the filament tow, which feed members may be inthe form of smooth rollers, cylindrical case drums or shaft drums; arotary drying cylinder, which can be heated, a crimping device, moreparticularly of the stuffing type, comprising a pair of feed rollers, astuffing chamber which inludes heating means, a weight-loaded retainingflap and a discharge channel; and a cutting device of any suitable typearranged directly behind the crimping device. The vat or vats for liquidtreatment may be substituted by one or more gutters which are providedwith several deflection rollers in order to pass the filament bundlethrough the gutters for a sufficient length of time.

It is preferred to provide on the way of the filament tow from the lastfibre treating device to the drying cylinder an instrument forcontrolling the tension of the filaments. A braking device acting bydeflection of the travelling direction of the filaments may be insertedbetween the crimping device and the cutting device, for instance, in theform of a creel brake, trellis grate, band brake or claw brake. It hasbeen found that this type of braking provides a simple compensation forthe loops possible forming in the filaments leaving the crimping device.

The heating of the stuffing chamber can be achieved in any suitablemanner, e. g., by a steam jacket or by electric resistance heating. Itis also contemplated within the purview of this invention to provide thestufiing chamber with a high frequency heating which permits aparticularly uniform heating of the filaments conglomerated in thechamber. A pneumatic device for opening and delivering the staple fibremay be joined to the cutting device. The air current used for opening,simultaneously may serve to treat the fibres with softening andconditioning agents or antistatically acting substances, by injectingthe respective agent into the inlet channel of the receiving tank,shortly before the fibres enter into the tank itself. The loose fibremass obtained in this manner in many instances on compression into balesmay be manufactured into slivers without a combing process, merely by acarding treatment.

Further objects, features, and details of the invention will be seenfrom the following detailed description in connection with theaccompanying drawings, showing some embodiments of apparatuses andequipments adapted for carrying out the invention, and which:

Fig. 1 is a diagrammatic view of a system adapted for carrying out themethod according to the present invention,

Fig. 2 is a longitudinal section, on a larger scale, of the crimpingdevice forming part of the system of Fig. 1,

Fig. 3 is a section online IIIIII of Fig. 2,

Fig. 4 is a section on line IVIV of Fig. 2,

Fig. 5 is a side view showing another form of a crimping device, usingtoothed wheels,

Fig. 6 is a section on line VIVI of Fig. 5,

Fig. 7 is a diagrammatic view of a modification of the system shown inFig. 1,

Fig. 8 is a longitudinal section of one embodiment of the heating devicediagrammatically shown in Fig. 1,

Fig. 9 is a section on line IXIX of Fig. 8, on a larger scale,

Fig. 10 is a side elevation, partly in section, showing a modificationof the heating device diagrammatically shown in Fig. 1,

Fig. 11 is a section on line XI-XI of Fig. 10,

Fig. 12 is a diagrammatic section of a further modification of theheating device diagrammatically shown in Fig. 1,

Fig. 13 is a section on line X[IIXIII of Fig. 12,

Fig. 14 is a diagrammatic plan view of a modified washing device, and

Fig. 15 is a section on line XV-XV of Fig. 14, drawn on a larger scale.

Similar reference numerals denote similar parts in the different views.

Referring now to the drawings, and first to Fig. 1, it will be seen thataccording to this embodiment the filaments drawn from the rolls 1 andcombined into a tow 2 are stretched between the roller systems 3 and 4,the stretching zone being heated to the required temperature by aheating device 5, if desired, e. g., by infrared radiators, as will behereinafter described. The filament tow 2 then passes over two rollers 7rotating in a washing vat or tub 6, the layering of the fibres inparallel turns being ensured through a comb 8. The tow then passes intothe tray 10 provided with deflecting rollers 9 where it is provided witha softener and delivered to a drying cylinder 11 including a guideroller 12 and a separating comb 13. On leaving the drying cylinder thetow 2 is seized by the feed rollers 14, 14 of the crimping device 14-20shown in greater detail in Figs. 2 to 4. Roller 14 has a projectingflange 26 projecting into a pcripheral groove 27 of roller 14', for safeengagement and driving of the tow 2 passing through the groove as shownand being forced into the stufiing channel 17 which is heated byelectrical heating means 15, 16, accommodated in the space 28 defined bythe outer jacket 29, and resiliently closed by a retaining flap 19 whichis urged against the mouth end of the channel 17 by a weighted lever 18.The electrical heating means may be adapted for high frequency heatingof the filaments. It will thus be understood that the filaments 2 underthe stufiing action exerted by the rollers 14, 14' are curled or crimpedin the channel 17 and as the stuffing pressure exerted by the filamentbundle is increasing, the retaining flap 19 will be raised, allowing thestuffed filaments to enter into the cooling channel 20, Fig. 1, fromwhich the filaments are drawn through a thread braking device 21 inwhich the filaments are forced to take a zig-zag course, into a cuttingdevice 22 in which the filaments are cut to the desired staple length.The staple cuts 23 occurring in this device are pneumatically seized bythe brisk air current indicated by the arrow 24, dispersed and conductedin a well opened condition, into the store tank 25 which is covered by awire screen. The material collected therein is compressed into bales andis now ready for dispatch. In many instances it can be worked up withoutcombing.

Figs- 5 and 6 show a modified device for crimping the fibres, comprisinggear wheels and 31 meshing with each other with a slight spacing betweenthe intermeshing teeth, so as to prevent injury to the filaments by toointensive compression during their passage between the intermeshingteeth. The gear wheels 30 and 31 are made hollow and traversed by steam,hot air or any other 1 store tank 25.

heating agent passed through tubes 32, 33 connected to the gear wheelsby suitable stuffing boxes 34.

A modified process according to the invention will now be described withreference to Fig. 7 in which the devices corresponding to the plant ofFig. 1 are designated with identical reference numerals. In this case,the filaments after the stretching between the roller aggregates 3 and 4are subjected to a further stretching action between the rolleraggregates 4 and 35, under action of heat produced by a heating device43 which will be hereinafter described in greater detail. The filamenttow is then passed through a tank 37 for wet heat treatment. The tank 37may be filled with water or with any suitable treating liquid which isheated by a heating device 41. Roller aggregates 38, 39, and 40 serve toguide the filament tow and to impart thereto a suitable tension whichmay be different between the roller aggregates 38 and 39 on one hand andbetween the roller aggregates 39 and 40 on the other hand. The rolleraggregate 39 can be adjusted in the direction of the arrows so as tovary the relative lengths of the operating paths 38-39 and 39-40 exposedto different stretching forces, or in other words, to vary the period oftime during which the filament tow is exposed to the different tensions.For the rest of the process the filaments are treated in the same way asdescribed With reference to Fig. 1, except that an injector device 42 isshown by which a softening agent can be sprayed onto the staple fibresas they are blown into the Under action of the air current blown in at24 the softening agent is uniformly distributed over the surface of thefibres.

Various possible forms of the heating device 43 will now be described ingreater detail with reference to Figs. 8, 9, or 10, 11, or 12, 13,respectively. Referring at first to Figs. 8 and 9, it will be seen thatthe tow 2 is passed through a heating chamber 43, located between theroller aggregates 4 and 35. The heating chamber 43 comprises a lowerpart 43' and an upper part 43" which is hinged to the lower part by ahinge indicated at 44 so as to facilitate opening of the heatingchamber, e. g., by winding up a pull rope 45 on a spindle 46.Heat-insulating material 47 is provided between the inner and outerwalls of the heating chamber 43, and infrared radiators 48 are securedto the inner walls of the heating chamber. Said infrared radiators maybe ofany suitable type. For instance, ceramic resistances may be used,consisting of a ceramic resistance material, or of resistance wire orsemi-conductors embedded in ceramic material.

According to Figs. 10'and 11, infrared lamps 49 are provided in aheating chamber 43. The wave length of the heat radiation of the lamps49 should be adapted to the absorption characteristics of the fibrematerial to be treated.

According to Figs. 12 and 13, the filament tow 2 is passed through aheating chamber 43 which is heated by heating coils 50 screened byscreening walls 51, and additionally heated by a fiow of hot inert gascirculated through a pipe system 52, under action of a blower 53, andheated by heating coil 54. An inlet branch including a throttle flap 56and an outlet branch 57 serve to renew the gas in the pipe, system. j

Figs. 14 and 15 show a washingdevice .of the gutter type which may beprovided instead of the washing tank 6, 7, 8, shown in Figs. 1 and 7. Inthis case, the filament tow is passed through gutters 58, overdeflecting rollers 59, and rinsed by hot water or another liquidtreating agent dripping onto the filaments from sprinkling pipes 60which, as shown in Fig. 15, are arranged above their gutters, theseparts being shown tilted by in Fig. '14 to permit a clear illustration.The water is collected in the gutter 58 and discharged'through thepipesystem 61 as diagrammatically indicated by the respective arrows.

Some practical examples of carrying out the invention will now bedescribed, referring to the drawings by the respective referencenumerals.

Example 1 A filament tow of a total titre of 200,000 den. and a singletitre of 16 den., produced of polymeric epsiloncaprolactam by continuouspolymerisation and subsequent spinning of the melt containing percent ofmonomeric and lowly polymeric lactam is stretched between the two rolleraggregates 3, 4, at a ratio of 1:4.0 to a single titre of 4.0 den. andthen passed, with a reduction of speed of 6%, caused by acorrespondingly lower speed of the drawing-off roller, and at a speed of40 meters per minme, over the two rollers 7 rotating in the washing tank6, in which the tow is treated with boiling water for a period of 80seconds, whereby the spinning preparations and the water-solubleconstituents of the fibre substance are dissolved, the latter down toabout 1.5% by weight. From the washing tank the tow is drawn at the samespeed into the tank 10 provided with deflecting rollers 9 and on thisoccasion is provided with about 0.5 percent by weight of a conventionalsoftening agent. The temperature of the bath with the softening agentamounts to 35 C. Then it passes to the drying cylinder 11 rotating atthe same speed and heated by steam to a surface temperature of 115 C.After a treatment period of 60 seconds the tow enters with an amount ofmoisture in the cable of 3.0 percent into the chamber 17 of the crimpingdevice which is heated to 125 C. (wall temperature). The crimped,largely conglomerated, still hot material is forced through thedischarging channel 20 while maintaining the curliness, i. e., withoutdraft, and then drawn into the cutting machine 22 through the brakingdevice 21. The staple fibres of 100 millimeters length obtained by thecutting are blown into the store tank 25 and then compressed into bales.The fibre material thus obtained can be worked up into top and spun innormal manner. It is even possible, in case of medium numbers of yarn,to do with cards only, since the fibre is pure and free from neps.

Example 2 I The fibre material is treated in the same way as describedwith reference to Fig. 1, but the period of drying on the dryingcylinder 11 is reduced to 25 seconds. The tow running off from thedrying cylinder 11 has a moisture of 5.5 percent by weight. It ispossible to obtain a titre of a dull lustre which is very similar towool. The curliness of the fibre (about 10 crimps per centimeter) isvery fast to boiling.

Example 3 A filament tow of polymeric epsilon-caprolactam with :1contents of water-soluble constituent of 11 percent by weight, with atotal titre of about 200,000 den. and a single titre of 8 den. isstretched in the same way as described in Example 1 wiLh a ratio of 1:4,to a single titre of 2 den., and then treated in the same way asdescribed in Example 1. The filaments arrive at the crimping device 15with an amount of moisture of about 2.5%. After the crimping thefilaments are cut to a staple length of 40 millimeters. The materialthus obtained'can be worked up to card sliver according to the cottonspinning process without preceding treatment with tannin.

Example 4 The filament tow is treated as in Example 3, except that thetime of stay on the drying drum 11 is reduced to 25 seconds as perExample 2. The material which has been crimped with an amount ofmoisture of about 5% shows a highe sta ili y and can be ked pon th rd nbetter th n tha ma e ac ording to Ex mpl Ea cample 5 A fila ent to opolymeric eps aprola tam o a total titre of 170,000 den. is stretched ata temperature of 8 170 and a ratio of 115.3 to a single fibre titre of1.5 den. and treated further as per Example 4. The finely crimped fibrecan be worked up in the fiat card without treatment with tannin and canbe spun into fine threads of a particularly high tensile strength.

Example 6 The filaments are treated as per Example 1, but using afilament tow of a total titre of 400,000 den., so that the titre of thebundle on stretching amounts to 100,000 den. The tow 2 coming from thedrying cylinder 11 with a temperature of C. and an amount of moisture of2.3 percent is passed into the stuffing chamber 17 of the crimpingdevice which has been heated to 50 C. The stuffing chamber is 30 mms.high, 30 mms. wide and mms. long. The load on the retaining flap 19 isadapted so that a specific pressure of 6.2 kilograms per centimetersquare, referring to the cross section at right angles to the axis ofthe stufiing channel, is exerted on the tow in the stuifing channel.After the cutting, a very curly material is obtained which can be spuninto particularly full yarns.

Example 7 The fibre material is treated as per Example 6, except thatthe stuffing channel 17 of the crimping device has a length of 600millimeters and the retaining flap 19 is opened. Owing to the frictionoccurring in the long stuifing chamber 17 a sufficient retainingpressure is produced, even though the flap 19 is open, so that thefilaments discharged from the crimping device have a good curliness.

Example 8 The fibre material is treated as per Example 6, except thatthe tow coming from the drying cylinder and having a temperature of 110C. and an amount of moisture of 0.8 percent only, is introduced into acrimping device whose stuffing chamber 17 is treated to 50 C. and has alength of 60 millimeters, a width of 15 millimeters, and a height of 15millimeters. The load on the retaining flap 19 is adapted so that thespecific pressure in the stuffing chamber 17 amounts to 13.3 kilogramsper centimeter square, referring to the cross section at right angles tothe axis of the stuffing channel. The curliness of this fibrecorresponds to that mentioned in Example 3.

While the invention has been described in detail with respect to certainnow preferred examples and embodiments of the invention it will beunderstood by those skilled in the art after understanding the inventionthat various changes and modifications may be made without departingfrom the spirit and scope of the invention and it is intended,therefore, to cover all such changes and modifications in the appendedclaims.

What is claimed is:

1. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds or" thegroup consisting of monomeric and lowly polymeric compounds, comprisingthe steps of combining the filaments into a tow of at least 40,000deniers, placing a tension on said tow to stretch the filaments to amultiple of their length, washing the tow with a hot aqueous washingagent, substantial drying the tow to a degree of moisture of less than6%, said washing and drying being performed while tension is maintainedon said tow, crimping the filaments in a continuous mechanical crimpingprocess at a temperature above room temperature while maintaining themoisture content at less than 6%, said steps directly succeeding eachother in this order, in a continuous process cutting the to into s plfibres nd op ning the stapl fibres by aetion of a jet of air blown atthe fibre material.

A m h d of p du i g ap fibres from xtruded. freshly formed filaments ofpolyamides composed substantially of condensation products of theepsilon-aminoca; proic acid containing water-soluble compounds of thegroup consisting of monomeric and lowly polymeric compounds, comprisingthe steps of combining the filaments into a tow of at least 40,000 den.,placing a tension on said tow to stretch the filaments to a multiple oftheir length, washing the tow with a hot aqueous washing agent,substantial drying the tow said washing and drying being performed whiletension is maintained on said tow, crimping the filaments in acontinuous mechanical crimping process at a temperature whilemaintaining the substantial dryness thereof above room temperature, andcutting them into staple fibres which are opened by action of a jet ofair blown at the fibre material, said steps directly succeeding eachother in this order, in a continuous process.

3. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing monomeric caprolactam, comprisingthe steps of combining the filaments into a tow of at least 40,000deniers, placing a tension on said tow to stretch the filaments to amultiple of their length, washing the tow with a hot aqueous washingagent, substantial drying the tow to a degree of moisture of less than6% said washing and drying being performed while tension is maintainedon said tow, crimping the filaments in a continuous mechanical crimpingprocess at a temperature above room temperature while maintaining themoisture content at less than 6%, said steps directly succeeding eachother in this order, in a continuous process cutting the tow into staplefibres and opening'the staple fibres by action of a jet of air blown atthe fibre material.

. 4. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds of thegroup consisting of monomeric and lowly polymeric compounds, comprisingthe steps of combining the filaments into a tow of at least 40,000deniers, placing a tension on said tow to stretch the filaments to amultiple of their length, washing the tow with a hot aqueous washingagent, subjecting it to a softening treatment, substantial drying thetow said washing, softening and drying being performed while tension ismaintained on said tow, crimping the filaments in a continuousmechanical crimping process at'a temperature above room temperaturewhile maintaining the substantial dryness thereof, said steps directlysucceeding each other in this order, in a continuous process cutting thetow into staple fibres and opening the staple fibres by action of a jetof air blown at the fibre material.

5. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds of thegroup consisting of monomeric and lowly polymeric compounds, comprisingthe steps of combining the filaments into a tow of at least 40,000deniers, placing a tension on said tow to stretch the filaments to amultiple of their length, washing the filaments with a hot aqueouswashing agent, and then substantially drying the tow to a degree ofmoisture of less than 4% said washing and drying being performed whiletension is'maintained on said tow, crimping the filaments in acontinuous mechanical crimping process at a temperature above roomtemperature while maintaining the moisture content at less than 4%, saidsteps directly succeeding each other in this order, in a continuousprocess, cutting the tow into staple fibres and opening the staplefibres by action of a jet of air blown at the fibre material.

6. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds of thegroup consisting of monomeric and lowly polymeric compounds, comprisingthe steps of combining the filaments into a tow of at least 40,000deniers, placing a tension on said tow to stretch the filaments to amultiple of their length, washing the tow with a hot aqueous washingagent, substantially drying the tow to a degree of moisture of less than6% said washing anddrying being performed while tension is maintained onsaid tow, crimping the filaments in a continuous mechanical crimpingprocess at a temperature above room temperature while maintaining themoisture content at less than 6% by stufiing, said steps directlysucceeding each other in this order, in a continuous process, cuttingthe tow into staple fibres and opening the staple fibres by action of ajet of air blown at the fibre material.

7. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds of thegroup consisting of monomeric and lowly polymeric compounds, comprisingthe steps of combining the filaments into a tow of at least 40,000deniers, placing a tension on said tow to stretch the filaments to amultiple of their length, washing the tow with a hot aqueous washingagent, substantially drying the tow said washing and drying beingperformed while tension is maintained on said tow, crimping thefilaments in a continuous mechanical crimping process at a temperatureand while maintaining the substantial dryness thereof above roomtemperature, cutting them into staple fibres which are opened by actionof a jet air blown at the fibre material, and treating the fibres with asoftening agent in the same operation, said steps directly succeedingeach other in this order, in a continuous process.

8. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds of thegroup consisting of monomeric and lowly polymeric compounds, comprisingthe steps of combining the filaments into a tow of at least 40,000deniers, placing a tension on said tow to stretch the filaments to amultiple of their length, at least the last phase of said stretchingtreatment being carried out at an elevated temperature of the filaments,washing the tow with a hot aqueous washing agent, substantially dryingthe tow said washing and drying being performed while tension ismaintained on said tow, crimping the filaments in a continuousmechanical crimping process at a temperature above room temperaturewhile maintaining the substantial dryness thereof, said steps directlysucceeding each other in said order, in a continuous process, cuttingthe tow into staple fibres and opening the staple fibres by action of ajet of air blown at the fibre material.

9. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds of thegroup consisting of monomeric and lowly polymeric compounds, comprisingthe following steps, succeeding each other in this order, in acontinuous process: combining the filaments into a tow of at least40,000 deniers, placing a tension on said tow to stretch the filamentsto a multiple of their length, at least the last phase of saidstretching treatment being carried out at an elevated temperature of thefilaments, washing the tow with a hot aqueous washing agent,substantially drying the tow, stretching once more at an elevatedtemperature of the filaments, said washing, drying and last mentionedstretching being performed while tension is maintained on said towcrimping the filaments'at a temperature above room temperature whilemaintaining the substantial dryness thereof, and cutting them intostaple fibres which are opened by action of a jet of air blown at thefibre material.

10. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds of thegroup consisting of monomeric and lowly polymeric compounds, comprisingthe steps of combining the filaments into a tow of at least 40,000deniers, placing a tension on said tow to stretch the filaments to amultiple of their length, washing the tow with a hot aqueous washingagent, substantially dry- '11 ing the tow said washing and drying beingperformed while tension is maintained on said tow, crimping thefilaments ina continuous mechanical crimping process at a temperatureabove room temperature by stuffing while containing 6 to 0.5% by weightof moisture and having a temperature of 80 to 130 C., said stepsdirectly succeeding each other in this order, in a continuous process,cutting the tow into staple fibres and opening the staple fibres byaction of a jet of air blown at the fibre material.

11. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing 9 to 12% by weight of epsiloncaprolaetam and water-soluble low polymers, comprising the steps ofcombining the filaments into a tow of at least 40,000 deniers, placing atension on said tow to stretch the filaments to a multiple of theirlength, washing the tow with a hot aqueous Washing agent, substantiallydrying the tow, said washing and drying being performed while tension ismaintained on said tow, crimping the filaments in a continuousmechanical crimping process at a temperature while maintaining thesubstantial dryness thereof above room temperature, said steps directlysucceeding each other in this order, in a continuous process, cuttingthe tow into staple fibres and opening the staple fibres by action of ajet of air blown at the fibre material.

12. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds of thegroup consisting of mono meric and lowly polymeric compounds, comprisingthe steps of combining the filaments into a tow of at least 40,000deniers, placing a tension on said tow to stretch the filaments to amultiple of their length, washing the tow with a hot washing agentcontaining additional treating agents, substantially drying the tow to adegree of moisture of less than 6% by weight said washing and dryingbeing performed while tension is maintained on said tow, crimping thefilaments in a continuous mechanical crimping process at a temperatureabove room temperature while maintaining the moisture content at lessthan 6%, said steps directly succeeding each other in this order, in acontinuous process, cutting the tow into staple fibres and opening thestaple fibres by action of a jet of air blown at the fibre material.

13. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds of thegroup consisting of monomeric and lowly polymeric compounds, comprisingthe steps of combining the filaments into a tow of at least 40,000deniers, placing a tension on said tow to stretch the filaments to amultiple of their length, washing the tow, with a hot washing agentcontaining a wetting agent, substantially drying the tow said washingand drying being performed while tension is maintained on said tow,crimping the filaments in a continuous mechanical crimping process at atemperature and while maintaining the substantial dryness thereof aboveroom temperature, said steps directly succeeding each other in thisorder, in a continuous process, cutting the tow into staple fibres andopening the staple fibres by action of a jet'of air blown at the fibrematerial.

14, A method of producing staple fibres from filament; of polyamidescomposed substantially of condensation products of theepsilon-.aminocaproie acid containing was tor-soluble compounds of thegroup consisting of mono: meric and lowly polymeric compounds,comprising the steps of combining the filaments into a tow of at least40,000 deniers, placing a tension on said'tow to stretch the filamentsto a multiple of their length, washing thG tow, with a hot washing agentcontaining a dispersing agent, substantially drying the tow said washingand drying being performed while tension is maintained on said tow,crimping the filaments in a continuous mechanical crimping process at atemperature and while maintaining the substantial dryness thereof aboveroom temperature, said steps directly succeeding each other in thisorder, in a continuous process, cutting the tow into staple fibres andopening the staple fibres by action of a jet of air blown at the fibrematerial.

15. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds of thegroup consisting of mono-. meric and lowly polymeric compounds,comprising the steps of combining the filaments into a tow of at least40,000 deniers, placing a tension on said tow to stretch the. filamentsto a multiple of their length, washing the tow with a hot aqueouswashing agent, substantially drying the tow said washing and dryingbeing performed while tension is maintained on said tow, crimping thefilaments in a continuous mechanical crimping process at a temperaturewhile maintaining the substantial dryness thereof above roomtemperature, and cutting them into staple fibres which are opened byaction of a jet of air blown at the fibre material and treated withconditioning agents, said steps directly succeeding each other in thisorder, in a continuous process.

16. A method of producing staple fibres from filaments of polyamidescomposed substantially of condensation products of theepsilon-aminocaproic acid containing water-soluble compounds of thegroup consisting of monomeric and lowly polymeric compounds, comprisingthe steps of combining the filaments into a tow of at least 40,000deniers, placing a tension on said tow to stretch the filaments to amultiple of their length, washing the towwith a hot aqueous washingagent, substantially drying the tow said washing and drying beingperformed while tension i maintained on said tow, crimping the filamentsin a continuous mechanical crimping process at a temperature above roomtemperature while maintaining the substantial dryness thereof, andcutting them into staple fibres which are opened by action of a jet ofair blown at the fibre material and treated with antistatic agents, saidsteps directly succeeding each other in this order, in a continuousprocess.

References Cited in the file of this patent UNITED STATES PATENTS MilesApr. 23, 1940 Hooper Apr. 11, 1944 OTHER REFERENCES

1. A METHOD OF PRODUCING STAPLE FIBRES FROM FILAMENTS OF POLYAMIDECOMPOSED SUBSTANTIALLY OF CONDENSATION PRODUCTS OF EPSILON-AMINOCAPROICACID CONTAINING WATER-SOLUBLE COMPOUNDS OF THE GROUP CONSISTING OFMONOOMERIC AND LOWLY POLYMERIC COMPOUNDS, COMPRISING THE STEPS OFCOMBINING THE FILAMENTS INTO A TOW OF AT LEAST 40.000 DENIERS, PLACING ATENSION ON SAID TOW TO STRETCH THE FILAMENTS TO A MULTIPLE OF THEIRLENGTH, WASHING THE TOW WITH A HOT AQUEOUS WASHING AGENT, SUBSTANTIALDRYING THE TOW TO A DEGREE OF MOISTURE OF LESS THAN 6%, SAID WASHING ANDDRYING BEING PERFORMED WHILE TENSION IS MAINTAINED ON SAID TOW, CRIMPINGTHE FILAMENTS IN A CONTINUOUS MECHANICAL CRIMPING PROCESS AT ATEMPERATURE ABOVE ROOM TEMPERATURE WHILE MAINTAINING THE MOISTURECONTENT AT LESS THAN 6%, SAID STEPS DIRECTLY SUCCEEDING EACH OTHER INTHIS ORDER, IN A CONTINUOUS PROCESS CUTTING THE TOW INTO STAPLE FIBRESAND OPENING THE STAPLE FIBERS BY ACTION OF A JET OF AIR BLOWN AT THEFIBRE MATERIAL.